Yes, the Champion is gapped at .035, but the NGK 6043 ILZKAR7A10 is designed for a gap of .040 and according to NGK literature, "Gap measured with laser precision throughout the production process" - I'm sure it can be re-gapped to .035 for use in your engine. Basically the only difference between the ILZKR7A and the ILZKAR7A10 is the gap. The ILZKR7A is just the more accurate application without the need for resetting the gap.
As to heat range; that's proprietary with some the higher the number the colder the plug, with others the higher the number the hotter the plug and a Champion 6 could be the same as a NGK 8, but other manufacturers may use alpha characters for heat range where a D might be the same as a heat range 10 with another manufacturer.
With NGK and Nippon Denso, the lower the number the hotter the plug - with Champion, the higher the number the hotter the plug.
EXCEPTION: NGK Racing Plugs: (Any NGK plug that begins with the letter “R”) For NGK Racing Plugs, the Heat Range is located AFTER the hyphen. Example: R5671A-10 has a Heat Range of 10. A colder plug would be # R5671A-11 (Heat Range 11), a hotter plug would be # R5671A-9 (Heat Range 9). Some NGK Racing Plugs are also available in half heat ranges. These are displayed as a 2 or 3 digit number after the hyphen. For example, R6120-85 has a 8.5 Heat Range and R6120-105 has a 10.5 Heat Range.
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